External fixation

ABSTRACT

External fixation systems, and methods for immobilizing joints or fractured bones. An external fixation system may include one or more clamp assemblies connected to one or more rod assemblies at polyaxial joints. Each rod assembly may be length adjustable, and may include a one-way locking mechanism to provisionally lock the length of the rod assembly, and additional locking mechanisms to permanently lock the length of the rod assembly. The system may be deployed pre-assembled as a unit to immobilize a joint or fracture. Another external fixation system further includes a spanning member extending transverse to the rod assemblies. Two or more external fixation systems may be deployed in a stacked configuration on one set of bone pins to immobilize two joints and/or fractures. The systems may be provided in kits including guiding instrumentation, bone pins and pin clamping assemblies for connecting the bone pins to the external fixation systems.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional of:

pending U.S. Provisional Patent Application No. 61/696,695, filed Sep.4, 2012, which carries Applicant's docket No. IMDS-5 PROV, and isentitled EXTERNAL FIXATOR; and

pending U.S. Provisional Patent Application No. 61/775,239, filed Mar.8, 2013, which carries Applicant's docket No. IMDS-15 PROV, and isentitled EXTERNAL FIXATOR.

The above-identified documents are incorporated herein by reference.

FIELD OF THE DISCLOSURE

This disclosure relates to systems, devices and methods for externalfixation. More specifically, this disclosure relates to systems forproviding external fixation to joints and/or fractured bones.

BACKGROUND OF THE INVENTION

The present disclosure relates to systems, devices and methods for longbone external fixation. Bone external fixation is useful in severalapplications, for example, for use in short-term stabilization oftraumatic injuries, long-term stabilization of traumatic injuries,short- or long-term stabilization of a joint, and limb-lengtheningstabilization during the healing process.

The systems, devices and methods described herein may be used forstabilization of a traumatic injury until a long-term stabilizationdevice can be applied. Short-term or temporary stabilization may allowsoft tissues to recover from trauma prior to definitive skeletalfixation: for example reduction of swelling, healing of open wounds,and/or healing of skin abrasions prior to open reduction and internalfixation. External fixation may also be used when transportation isrequired from the site of initial care, such as a local or ruralhospital to a secondary site with appropriate trauma capabilities, suchas a regional trauma center. Short-term stabilization may also be usedfor injuries that occur during periods of time when appropriate traumacare is not available, such as after hours, until a skilled clinicianbecomes available. Short-term stabilization may be appropriate inbattlefield or field hospital situations. There is a need for externalfixation systems and methods which are simple, easy, and affordable.

In fixation systems known in the art, significant time may be spentassembling clamp bodies on the back table. In many cases, the samecomponents are used each time. During implantation over the fracture orjoint, sliding rods, moving clamps and other numerous parts requiringindividual adjustment make the application and tightening of the framecumbersome. There is a need for a frame that requires no pre-assemblyand can simply be placed over the fracture or joint, have the first setof pins placed on one side of the joint, stretch the frame over thejoint and place the second set of pins as desired on the second side ofthe joint. There would be no assembly and no possibility of rods slidingout of the clamps in such an arrangement.

In many situations, before an external fixation frame can be lockeddown, the fracture/joint must be restored to its proper length. In orderto do this, the limb must be stretched against the natural tension inthe muscles. This force is significant, as some surgeons report thatthey pull until “their feet begin to slide on the floor”. In systemsknown in the art, the surgeon must hold this tension as an assistanttightens all the clamps in the frame. There is a need for a one-waymotion lock that holds the limb length once it has been established.This would allow the surgeon to make minor adjustments as necessary andlock the frame in a less technically demanding manner and potentiallywithout as much assistance from other scrubbed personnel as is neededwith systems known in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention will now be discussed withreference to the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope.

FIG. 1 is a perspective view of an external fixation system including afirst clamping assembly, a second clamping assembly, and two rodassemblies captured in the first and second clamping assemblies, theexternal fixation system mounted on a plurality of bone pins;

FIG. 2 is a top-down view of the external fixation system of FIG. 1;

FIG. 3 is an enlarged perspective view of the first clamping assembly ofFIG. 1, including two bone pins;

FIG. 4 is an exploded view of a clamping assembly of FIG. 1;

FIG. 5 is a cross-sectional view of the clamping assembly of FIG. 1taken along line A-A of FIG. 2;

FIG. 6 is a cross-sectional view of the clamping assembly of FIG. 1taken along line B-B of FIG. 2;

FIG. 7 is a perspective view of a rod assembly of FIG. 1;

FIG. 8 is an exploded view of the rod assembly of FIG. 1;

FIG. 9 is a longitudinal cross-sectional view of a rod assembly of FIG.1 taken along line C-C of FIG. 2;

FIG. 10 is an end view of a rod assembly of FIG. 1, with a tube plugremoved in order to show detail of a locking clamp;

FIG. 11 is a top-down view of a kit including a tray, the externalfixation system of FIG. 1, a plurality of bone pins, a drill guide,drill sleeves, and a wrench;

FIG. 12 is a perspective view of another external fixation system,secured to a tibia, a calcaneus, and a metatarsal to span an anklejoint, the system including a clamping assembly, two rod assemblies, twoclamping strut assemblies, a pin clamp assembly, a spanning member and aplurality of bone and calcaneal pins;

FIG. 13 is a side view of the external fixation system of FIG. 12secured to the tibia, calcaneus, and metatarsal;

FIG. 14 is a perspective view of the external fixation system of FIG.12;

FIG. 15A is a side view of a clamping strut of the external fixationsystem of FIG. 12;

FIG. 15B is a posterior perspective view of the clamping strut of FIG.15A;

FIG. 16 is an exploded anterior perspective view of a clamping strutassembly of the system of FIG. 12;

FIG. 17A is an anterior view of the spanning member of the system ofFIG. 12; FIG. 17B is a posterior view of the spanning member; FIG. 17Cis a superior view of the spanning member;

FIG. 18A is a side view of the pin clamp assembly of FIG. 12; FIG. 18Bis a top view of the pin clamp assembly;

FIG. 19 is an anterior perspective view of a two-level external fixationsystem mounted to span a knee joint and an ankle joint, the systemincluding the knee spanning external fixation system of FIG. 1 and theankle spanning external fixation system of FIG. 12 in a stackedconfiguration, mounted on a common set of tibial bone pins;

FIG. 20 is a side view of the two-level external fixation system of FIG.19;

FIG. 21 is a perspective view of yet another external fixation system,the system including two clamping assemblies, a rod assembly, and aplurality of bone pins;

FIG. 22 is a perspective view of a clamping assembly and bone pins ofthe external fixation system of FIG. 21;

FIG. 23 is an exploded perspective view of the clamping assembly andbone pins of FIG. 22;

FIG. 24 is another exploded perspective view of the clamping assemblyand bone pins of FIG. 22, from a different viewpoint;

FIG. 25 is a cross-sectional view of the clamping assembly of FIG. 22,comparable to FIG. 5;

FIG. 26 is another cross-sectional view of the clamping assembly of FIG.comparable to FIG. 6; and

FIG. 27 is a perspective view of the external fixation system of FIG. 21secured to a radius and a metacarpal to span a wrist joint.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present disclosure relates to external fixation systems and methodsfor their use. Those of skill in the art will recognize that thefollowing description is merely illustrative of the principles of thetechnology, which may be applied in various ways to provide manydifferent alternative embodiments. This description is made for thepurpose of illustrating the general principles of this technology and isnot meant to limit the inventive concepts in the appended claims. Whilethe present disclosure is made in the context of knee or ankle joint orfracture fixation for the purposes of illustrating the concepts of thedesign, it is contemplated that the present design and/or variationsthereof may be suited to applications in the arm, wrist, finger, toe,spine, or other bones or joints.

The technology described herein may relate to an external fixation clampthat utilizes at least one polyaxial joint to provide for a highlyadaptable connection between a bone and a stiffening rod.

The devices, kits and methods of the present disclosure can provide anexternal fixation system which is economically disposable. The systemsof the present disclosure may be manufactured at such a low cost thatthey can be considered disposable after one use. For example, a kit ofthe present disclosure may be made for a manufacturer's suggested retailprice (MSRP) of about $500. Each of the external fixation systemsdisclosed herein may be provided pre-assembled in a kit which may alsoinclude tools and/or fixation members such as pins. In a method of use,bone pins may be fixed in bone portions of a patient, to span a fractureand/or an anatomical joint. The pre-assembled external fixation systemis mounted on the bone pins as a single piece or unit, and provisionallylocked by pulling one end of the system away from the opposite end, thussetting the fracture and/or immobilizing the anatomic joint. After theprovisional locking, which holds the joint or fracture immobilized,individual connections and clamps of the system may be adjusted andfurther locked down. The external fixation system may remain on thepatient for a short term period of time which may include transportationtime. For example, a complex ankle fracture such as a pylon (pilon)fracture might be initially treated with an external fixator untilswelling lessens one or two weeks later and it is safer to make skinincisions to treat the fracture definitively. The patient might betransported to another hospital or rehabilitation facility between thetime of initial external fixator placement and definitive surgery. Inanother example, one or more systems of the present disclosure may beused on a patient in a battlefield or at an accident site, and left inthe locked down configuration on the patient through transportation to ahospital, where surgery or other long-term means are used to stabilizethe fracture or joint.

In this specification, standard medical directional terms are employedwith their ordinary and customary meanings. Superior means toward thehead. Inferior means away from the head. Anterior means toward thefront. Posterior means toward the back. Medial means toward the midline,or plane of bilateral symmetry, of the body. Lateral means away from themidline of the body. Proximal means toward the trunk of the body. Distalmeans away from the trunk.

In this specification, a standard system of three mutually perpendicularreference planes is employed. A sagittal plane divides a body intobilaterally symmetric right and left portions. A coronal plane divides abody into anterior and posterior portions. A transverse plane divides abody into superior and inferior portions.

In an aspect of a method for external fixation of a limb, the limbhaving a first bone portion and a second bone portion, the methodincludes: securing a first bone pin to the first bone portion; securinga second bone pin to the second bone portion; attaching a pre-assembledexternal fixation system to the first hone pin, the external fixationsystem including: first and second clamp assemblies, first rodassemblies, and a one-way locking mechanism; the first rod assemblyjoined to each of the first and second clamp assemblies, the first andsecond clamp assemblies at opposite longitudinal ends of the first rodassemblies; the first clamp assembly received over the first bone pin;attaching the external fixation system to the second bone pin, thesecond clamp assembly received over the second bone pin; applyingtension to distract the first clamp assembly longitudinally away fromthe second clamp assembly to increase a length of the external fixationsystem between the first clamp assembly and the second clamp assembly;and releasing the tension on the first clamp assembly, wherein when thetension on the first clamp assembly is released the one-way lockingmechanism automatically engages to prevent the length of the externalfixation system from decreasing.

In an embodiment, the method may include: opening a package; andremoving the pre-assembled external fixation system as a single unitfrom the package

In another embodiment, each rod assembly includes a removable tab, themethod including: removing the tab to activate the one-way lockingmechanism, wherein prior to removal of the tab, the external fixationsystem is freely adjustable to increase or decrease the length of theexternal fixation system between the first clamp assembly and the secondclamp assembly;

In yet another embodiment, the external fixation system includes asecond rod assembly, the second rod assembly joined to each of the firstand second clamp assemblies.

In yet another embodiment, the first clamp assembly is identical to thesecond clamp assembly, and the first rod assembly is identical to thesecond rod assembly.

In yet another embodiment, the one-way locking mechanism automaticallyengages the rod assembly to prevent the length of the external fixationsystem from decreasing.

In yet another embodiment, the one-way locking mechanism automaticallyengages the rod assembly at a non-discrete location to prevent thelength of the external fixation system from decreasing.

In yet another embodiment, the rod assembly includes an inner tubularmember received in an outer tubular member, wherein the one-way lockingmechanism is a first locking mechanism, wherein the one-way lockingmechanism is mounted to the outer tubular member, wherein activating theone-way locking mechanism further includes: directly engaging theone-way locking mechanism with the inner tubular member to prevent theinner tubular member from translating relative to the outer tubularmember in a first direction.

In yet another embodiment, the one-way locking mechanism includes acollar encircling the inner tubular member, wherein the collarfrictionally engages with the inner tubular member to prevent the innertubular member from translating relative to the outer tubular member inthe first direction.

In yet another embodiment, the method includes: activating a secondlocking mechanism to further prevent the inner tubular member fromtranslating relative to the outer tubular member in the first directionand also in a second direction opposite the first direction.

In yet another embodiment, the rod assembly further includes the secondlocking mechanism, the second locking mechanism including a clampencircling the outer tubular member, the method further including:compressing the clamp around the outer tubular member; and compressingthe outer tubular member around the inner tubular member.

In yet another embodiment, the method includes: activating a thirdlocking mechanism to further prevent the inner tubular member fromtranslating relative to the outer tubular member.

In yet another embodiment, the rod assembly further includes the thirdlocking mechanisms, the third locking mechanism including a plugreceived in the inner tubular member, the method further includingdrawing the plug within the inner tubular member to expand a portion ofthe inner tubular member.

In yet another embodiment, the method includes: polyaxially adjustingthe position of the first rod assembly relative to the first clampassembly; and compressing the first clamp assembly about the first rodassembly to lock the position of the first rod assembly relative to thefirst clamping assembly.

In yet another embodiment, the method includes: locking the firstclamping assembly to the first bone pin.

In yet another embodiment, the first clamping assembly houses a firstfixation plate and a second fixation plate, wherein locking the firstclamping assembly to the first bone pin further includes: passing thefirst bone pin through the first and second fixation plates; anddeforming the first and second fixation plates to bind against the firstbone pin.

In yet another embodiment, the method includes: passing a third bone pininto the first clamping assembly; and securing the third bone pin to thelimb.

In an aspect of an external fixation system, the system includes: afirst clamp assembly; a second clamp assembly; a first rod assemblysecured to and extending between the first clamp assembly and the secondclamp assembly, the first rod assembly including a first tubular memberand a second tubular member received in the first tubular member; and aone-way locking mechanism which limits axial translation between thefirst tubular member and the second tubular member, the one-way lockingmechanism having an unlocked configuration and a locked configuration;wherein the external fixation system has a length measured between thefirst clamp assembly and the second clamp assembly: wherein when theone-way locking mechanism is in the unlocked configuration the secondtubular member can freely translate relative to the first tubular memberto increase or decrease the length of the external fixation system; andwherein when the one-way locking mechanism is in the lockedconfiguration second tubular member can freely translate relative to thefirst tubular member to increase the combined length of the externalfixation system but is prevented from translating relative to the firsttubular member to decrease the length of the external fixation system.

In an embodiment, the external fixation system includes a second rodassembly secured to and extending between the first clamp assembly andthe second clamp assembly, wherein the first clamp assembly is identicalto the second clamp assembly, and wherein the first rod assembly isidentical to the second rod assembly.

In another embodiment, the second tubular member can axially translatein a first direction to increase the length of the external fixationsystem and in a second direction opposite the first direction todecrease the length of the external fixation system.

In yet another embodiment, in the locked configuration the one-waylocking mechanism engages the first rod assembly to prevent the lengthof the external fixation system from decreasing.

In yet another embodiment, the one-way locking mechanism furtherincludes a collar encircling the second tubular member, wherein, in thelocked configuration, the collar binds against the second tubular memberto prevent translation of the second tubular member in the seconddirection.

In yet another embodiment, the one-way locking mechanism is a firstlocking mechanism, the system further including a second lockingmechanism to further prevent the second tubular member from any motionrelative to the first tubular member.

In yet another embodiment, the rod assembly further includes the secondlocking mechanism, the second locking mechanism including a clampencircling the first tubular member, wherein the clamp is compressibleabout the first tubular member to compress the first tubular memberaround the second tubular member to prevent any motion relative to thefirst tubular member.

In yet another embodiment, the external fixation system includes a thirdlocking mechanism which engages the first and second tubular members.

In yet another embodiment, the third locking mechanism includes a plugreceived in the second tubular member, wherein drawing the plug withinthe second tubular member expands a portion of the second tubular memberto fit tightly within the first tubular member.

In yet another embodiment, the first clamp assembly includes a sphericalclamping surface and the first rod assembly includes a sphericalportion, the spherical portion received within the spherical clampingsurface to form a polyaxial joint between the first clamp assembly andthe first rod assembly.

In yet another embodiment, the first clamp assembly further includes alocking screw, wherein tightening the locking screw compresses thespherical clamping surface around the spherical portion to lock theposition of the first rod assembly relative to the first clampingassembly.

In yet another embodiment, the external fixation system includes asecond rod assembly including a second spherical portion, wherein thefirst clamping assembly further includes a second spherical clampingsurface, the second spherical portion received within the secondspherical clamping surface to form a polyaxial joint between the firstclamp assembly and the second rod assembly, wherein tightening thelocking screw simultaneously locks the positions of the first and secondrod assemblies relative to the first clamping assembly.

In yet another embodiment, the external fixation system includes a firstbone pin, wherein the first clamping assembly houses a first fixationplate and a second fixation plate, wherein the first bone pin passesthrough the first fixation plate and the second fixation plate, and thefirst and second fixation plates are deformable to bind against thefirst bone pin and fix the position of the first bone pin relative tothe first clamping assembly.

In yet another embodiment, the external fixation system includes aremovable tab attached to the one-way locking mechanism, wherein theremovable tab holds the one-way locking mechanism in the unlockedconfiguration, wherein removal of the tab from the one-way lockingmechanism converts the one-way locking mechanism to the lockedconfiguration.

Referring to FIGS. 1 and 2, an external fixation system 500 includes afirst clamping assembly 502, a second clamping assembly 504, a first rodassembly 506 and a second rod assembly 508. In an embodiment, externalfixation system 500 may be referred to as a knee spanning system orjoint spanning system, although external fixation system 500 may also beused to span a fracture, osteotomy, epiphyseal plate, or otherdiscontinuity between bone portions. The rod assemblies 506, 608 extendbetween and connect the clamping assemblies 502, 504 into the singlesystem 500. The rod assemblies 506, 508 may be scaled to an appropriatesize for the knee or other anatomical site. In some embodiments, thesecond rod assembly 508 may be omitted. The connections between the rodassemblies and clamping assemblies are polyaxially adjustable. Theclamping assemblies may be referred to as support elements or members,as they support the rod assemblies. The rod assemblies may be referredto as variable length or telescoping elements, struts, or members, asthe length of each is adjustable. The external fixation system 500 maybe referred to as a frame. The first and second clamping assemblies maybe mirror images, or may be identical to one another, as may the firstand second rod assemblies. Using identical assemblies in a system mayenable the entire system to be produced more cheaply and/or quickly thana system in which each separate component or assembly is unique. Forexample the system 500 with identical assemblies 502, 504 and 506, 508may require fewer forms and unique production processes than a systemhaving multiple unique and non-identical components. Assembly may alsobe faster as there may be fewer steps, and certain assembly steps may berepeated.

In use, system 500 can be secured to the patient in one piece, as aunit. First clamping assembly 502 may be fixed to a first bone portionby one or more fixation pins 510. Bone screws, bone pins, wires, and/orother fasteners may be used in place of or in combination with fixationpins 510. Second clamping assembly 504 may be fixed to a second boneportion by additional fixation pin(s) 510. The rod assemblies 506 and508, extending between the clamping assemblies, may span a joint orfracture between the first and second bone portions. After the clampingassemblies 502, 504 are fixed to the bone portions, the rod assemblies506, 508 may be lengthened or shortened to a desired length andprovisionally locked to stabilize the joint or fracture. Following theprovisional locking, the polyaxial connections of the assembly may beadjusted, then more permanently locked.

Referring to FIGS. 3-6, clamping assembly 502 is shown in more detail.Clamping assembly 504 may be a mirror image, or may be identical toclamping assembly 502 and will not be described in further detail; thedescription of clamping assembly 502 also applies to clamping assembly504. Clamping assembly 502 includes a clamp body 520 which is formed asa single piece. Clamping assembly 502 further includes first and secondfixation bolts 522, 524; first, second, third and fourth fixation plates526, 527, 528 and 529; a clamping bolt 530; first nut 532; and secondnut 533. The fixation plates may be referred to as locking plates. Therod assemblies 506, 508 are polyaxially adjustably connected to theclamping assembly 502 via a first clamp 534 and a second clamp 536 whichare formed as part of the clamping body 520. In some embodiments, thesecond clamp 536 may be omitted. Two bone pins 560, 562 extend throughthe clamping body 520 to fix the clamping assembly 502 to a boneportion. In another embodiment, only one bone pin may be used.

Referring to FIGS. 2, 4 and 5, clamp body 520 may be cruciform orplus-shaped and includes an upper or first surface 512 and a lower orsecond surface 514 opposite the first surface. The clamp body 520further includes a first arm 538 and a second arm 540 which extend alonga first axis 541, perpendicular to the first and second clamps 534, 536which extend along a second axis 535. First axis 541 may be parallel tothe longitudinal lengths of rod assemblies 506, 508 when the system 500is in a neutral or orthogonal arrangement. Two bolt openings 544, 546extend through the clamping body 520 in the same direction as the pinopenings 542, 552 described below. In the example shown, the bolt andpin openings extend in a direction perpendicular to the first axis 541and the second axis 535. A first slot 548 is recessed into the firstsurface 512, and a second slot 550 is recessed into the second surface514, opposite the first slot. The first and second slots are elongated,occupying the majority of the length of the first and second arms 538,540, and slots are parallel with first axis 541. A plurality of pinopenings or bores 542 extend through the arms between the first andsecond slots 548, 550, each pin bore sized to receive a bone pin 510.First and second fixation plates 526, 528 are housed in the first slot548, and third and fourth fixation plates are housed in the second slot550. Each fixation plate 526, 527, 528 and 529 includes at least oneplate pin opening 552, and one of a threaded plate bolt opening 554 or anon-threaded plate bolt opening 555. Each fixation plate 526, 527, 528and 529 is elongated, having a first extension 556 and a secondextension 558.

The bone pins 560, 562 are received in pin openings 542 of clamp body520. As seen in FIGS. 4 and 5, each bone pin may pass through a platepin opening 552 in a fixation plate, through the first slot 548, througha pin bore 542, through the second slot 550, and out through a plate pinopening 552 in another fixation plate. The opening for the pins may benon-threaded and/or smooth, to allow the pins 560, 562 to initially beaxially translatable relative to the arms 538, 540. The translationallows for adjustability of the height of the system 500 relative to apatient's limb, which may be advantageous if there are tissue swelling,open wounds, and/or skin abrasions on the limb. It is appreciated thatthe bone pins may be placed in one or any combination of the pinopenings 542.

Referring to FIG. 5, the first fixation bolt 522 passes through anon-threaded bolt opening 554 in first fixation plate 526, into the slot548, through a bolt opening 544 and out through second slot 550 and athreaded plate bolt opening 555 in second fixation plate 527. As thethreads of bolt 522 engage threaded plate bolt opening 555, the secondfixation plate 527 is drawn toward the first fixation plate 526, and oneor both of fixation plates 527, 526 may be elastically or plasticallydeformed. The plate pin openings 552 frictionally hind against pin 562,preventing it from further axial translation. As the plates 526, 528deform they may bow and decrease in length, which pushes the pin 562against the side wall of the pin bore 542. This force creates asecondary locking action relative to the pin 562. The bolt 524 passesthrough bolt opening 554 in third fixation plate 528, through a boltopening 544 and out through second slot 550 and a threaded plate boltopening 555 in fourth fixation plate 529. Bolt 524 engages with plates528, 529 in the same manner as described for bolt 522 to fix pin 560. Itis appreciated that in other embodiments, other methods of pin captureor fixation known in the art may be used.

Turning to FIGS. 4 and 6, clamps 534, 536 are shaped to retain or clamprod assemblies 506, 508 while allowing telescoping movement of the rodassemblies to lengthen or shorten the rod assemblies. Clamp 534 has aninner clamping surface 570 which is spherical in the illustratedembodiment; in other embodiments the clamping surfaces may be partiallyspherical, conical, cylindrical, flat, polygonal, or another shape. Inthe embodiment shown, the clamps 534, 536 may be said to hold thecorresponding spherical portions 612, 614 captive because the innerclamping surfaces 570, 580 are wide enough, parallel to axis 541, tocover an equatorial diameter, or great diameter, of the correspondingspherical portion 612, 614 sufficiently to interfere with disassembly atlow loads. The inner clamping surface 570 is interrupted by a clamp gap572 bounded by opposing first and second clamp surfaces 574, 576.Similarly, clamp 536 has a spherical inner clamping surface 580, clampgap 582, and first and second clamping surfaces 584, 586. In the exampleshown the inner clamping surfaces 570, 580 are smooth but in analternative embodiment they may be ridged or roughened. A bore 590extends through clamps 534 and 536, parallel to second axis 535,intersecting clamp gaps 572, 582. Bore 590 also intersects with secondslot 550 at the center of the clamp body 520. The bore 590 includes afirst recess 592 at one end and a second recess 594 at the opposite end.A chamber 596 extends lengthwise within the clamp body 520 between thefirst clamp 534 and the second clamp 536, and may provide for weightreduction for the clamp body. Clamping bolt 530 extends through bore 590and engages nut 532. As the clamping bolt 530 engages the nut 532, thenut 532 is captured in second recess 594. Further actuation of bolt 530draws nut 532 toward the bolt head, engaging recess 594 and closing gaps572, 582. Nut 533, which may be a wing nut, may also be actuated by handto tighten bolt 530. As seen in FIG. 1, when rod assemblies 506, 508 areassembled with clamps 534, 536 as shown and bolt 530 is tightened asdescribed, the rod assemblies are gripped in the clamps and preventedfrom any movement, for example axial, rotation, or polyaxial, relativeto the clamp body 520. Nut 533 and bolt 530 may include coarse pitchthreads for quick tightening.

Referring to FIGS. 7-10, rod assembly 506 is shown in more detail. Rodassembly 508 may be a mirror image, or may be identical to rod assembly506 and will not be described further detail. Rod assembly 506 includesan outer or first tubular element 600, an inner or second tubularelement 602, a locking screw 604 and a rod clamp assembly 606. The firsttubular element 600 has a first end 601 and a second end 603 and shaft609 extending therebetween; the second tubular element has a first end605 and a second end 607 and a shaft 619 extending therebetween. Thefirst tubular element 600 is larger in diameter than and coaxiallyreceives a portion of the second tubular element 602. The tubularmembers may be circular in cross-section as shown, or in otherembodiments may be square, rectangular, triangular, or any otherpolygonal shape in cross-section. The tubular elements may also bereferred to as rods, rod elements, or rod members.

A first tube plug 608 is joined to the first end 601 of first tubularelement 600 and a second tube plug 610 is joined to the second end 607of second tubular element 602. An inner plug 611 fits inside the firstend 605 of the inner tubular element 602. The tube plugs 608, 610 haveconvex spherical portions 612, 614 which are complementarily shaped tothe concave spherical inner clamping surfaces 570, 580 of the clamps534, 536. First tube plug 608 further includes a neck 613 and anattachment portion 617, and second tube plug 610 further includes a neck615 and an attachment portion 619. The necks 613, 615 may be smaller indiameter than the respective, spherical portions 612, 614, and therespective, inner and outer tubular elements 600, 602. The attachmentportions 617, 619 may be annular and hollow, and sized to be received inthe respective tubular elements 600, 602. The large and small tube plugs608, 610 may be made from machined aluminum. During manufacture they maybe assembled to the associated tubes through insertion, bonding, gluingor threading, among other processes.

A line, chain, tether, or other connecting element may extend betweeninner plug 611 within second tubular element 602 and first tubularelement 600, to prevent inadvertent disconnection between the tubularelements 600, 602. As seen in FIG. 9, a line 629 may be tethered toinner plug 611, extend through the bore of outer tubular element 600,and be tethered to a cap 631 received in tube plug 608. Line 629 may beof sufficient length to allow axial translation between the tubularelements; for example line 629 may be approximately the length of outertubular element 600. In other embodiments, other retention featuresknown in the art may be used to prevent disconnection between the firstand second tubular elements.

The spherical portions 612, 614 of the plugs may feature an exteriorpattern or texture to enhance the locking strength of the polyaxialclamps. A first pattern may be a negative feature, in which valleys,grooves or slots are cut into the outer surface of the sphere. This iseffective where the clamp surface has sufficient compliance to deformelastically or plastically into the negative features. A second patternmay be a positive feature, such as spikes or sharp ridges that extendfrom the native, or nominal, spherical surface. These positive featuresare intended to press or cut into the clamp surface in order to create amechanical interlock between the spherical portion and the clamp. Thefirst pattern may enhance the clamping forces between the two elementswithout damaging either component. The second pattern may permanentlydeform one of the two elements, and may be less likely to be reversible.The embodiments disclosed herein may include the first or secondpatterns, a combination of the two, neither pattern, or another pattern.In other embodiments, texture may be provided by coatings or materialdeposits. The spherical portions may include openings that serve asdrain holes, to permit fluid drainage when a patient bathes.

When assembled with the clamps 534, 536, as in FIGS. 1 and 3 forexample, the spherical portions 612, 614 form polyaxially adjustablejoints, allowing rotational motion about multiple axes. The polyaxialrange of notion of the system 500 is a function of the thickness of theclamps 534, 536 parallel to axis 541, the diameter of the sphericalportions 612, 614 of the tube plugs and the diameter of the necks 613,615 that connect the spherical portion to the tubular element. Thedepicted embodiment features +/−30 degrees of motion at each polyaxiallyadjustable joint. In another embodiment, the range of motion may be+/−45 degrees at each polyaxially adjustable joint. If additional rangeof motion is required, this can be accomplished by reducing thethickness of the clamps, increasing the diameter of the sphericalportions, and/or decreasing the diameter of the neck regions. As thediameter of the neck is reduced, the tube wall thickness may be thickerin order to maintain the same strength. An optimization exercise can beemployed to determine the diameter and wall thickness that maximizesboth the polyaxial range of motion and the component strength. It isappreciated that the locations of the spherical portions and clampingsurfaces can also be reversed to achieve a polyaxial connection betweenthe clamp assembly and a rod assembly. For example, in an embodiment theclamp body 520 may include a convex spherical portion and a rod assembly506 or 508 may include a concave spherical clamping surface. In anotherembodiment, spherical portions 612, 614 may be split spheres which areexpanded from within to lock with the spherical clamping surfaces 570,580.

The spherical portions 612, 614 may have any size diameter according tothe intended use of the external fixator embodiment. As the diameter ofa spherical portion increases, the clamping force necessary to lock outmotion between a spherical portion and its respective spherical clampingsurface decreases, and can be reduced to a level that can be locked byfinger tightening a wing nut, knob, lever, bolt, or the like. In anembodiment, the diameter of the spherical portion is 0.75 inches orlarger. In another embodiment, the diameter of the spherical portion is1.0 inch or larger. In another embodiment, the diameter of the sphericalportion ranges from 1.25 to 1.75 inches. Embodiments with sphericalportions of 0.75 inches or larger may be suited to use in the femur,knee, tibia, ankle, and/or foot.

It is appreciated that other embodiments contemplated within the scopeof the disclosure include polyaxially adjustable joints at otherlocations on the systems disclosed herein. In another embodiment,polyaxially adjustable joints may be located at one or more locationsalong the length of the rod assemblies, instead of or in addition to thepolyaxially adjustable joints at the ends of the rod assemblies, forexample, they may be formed between first and second rod elements of therod assemblies. In another embodiment, U-joints allowing rotationalmovement about two axes may be formed between the rod assemblies and theclamping assemblies. In another embodiment, polyaxially adjustablejoints may be formed on the clamping assemblies instead of at theconnections between the clamping assemblies and the rod assemblies. Inanother embodiment, polyaxially adjustable joints may be formed betweenthe bone pins and the clamping bodies. Other embodiments may mix andmatch the joint locations disclosed herein.

The outer 600 and inner 602 tubes may be specified as standard sized,thin-walled aluminum tubing. They may also be manufactured from carbonfiber reinforced polymer or other materials that provide the desiredstiffness and ability to associate with the tube plugs. The shafts 609,619 may be smooth to facilitate sliding between them. Indicia 646 may bepresent on the outsides of the tubular elements to indicate the lengthof the rod assembly. In some embodiments, grooves may be present on theoutside of tubular element 602 to catch binding collar 624 at discreteand/or predetermined positions. In some embodiments, a ratchetingconnection may be formed between the first and second tubular elements.

In an embodiment, the rod clamp assembly 606 may be described as a splitcollar locking device. It may be bonded to the end of the outer tubularelement 600 and is oriented to a short slot 616 in that tube. In theexample shown in FIG. 8, the rod clamp assembly 606 includes a lockingcollar 620, a pin 622, a binding collar 624, a screw 626, a retentionpin 628, a spring 630 and a retainer 632. The binding collar 624 isreceived in an annular recess 621 of the locking collar 620, and ishinged to the locking collar via pin 622. A tongue 625 protrudes fromthe binding collar 624. The retention pin 628 extends through a bore inthe binding collar 624, through a pin bore 629 in the locking collar,through spring 630 and is captured by retainer 632. The locking collar620 further includes a circular bore 660 which is interrupted by acollar gap 662. A first shoulder 664 and a second shoulder 666 are onopposite sides of the bore gap 662. Screw 626 is received in a screwbore 627 of the locking collar 620. The outer tubular element 600 isreceived in bore 660, with second end 603 seated against a flange 623.

The rod clamp assembly 606 further includes a tab member 670, which isremovable to allow the rod clamp assembly 606 to be actuated toprovisionally lock the first and second tube members 600, 602 in a fixedaxial or length relationship. Tab member 670 includes a pair of tabextensions 672. As seen in FIG. 10, binding collar 624 is received inlocking collar 620. In an unlocked configuration, tab member 670 isattached to the rod clamp assembly 606 with tab extensions 672 are oneither side of tongue 625, captured between the tongue and the shoulders664, 666. The presence of the tab member 670 keeps collar gap 662 open,allowing tubular members 600, 602 to axially move relative to oneanother in both directions, by preventing bore 660 from clamping aroundtubular members 600, 602 and provisionally locking the tubular memberstogether. In use, tab member 670 may be present on the system 500 whenit is removed from packaging, and allows telescoping adjustment of thelength of system 500, in either axial direction, to shorten or lengthenthe system 500.

A provisional, or temporary locking mechanism 650 allows the tubes 600,602 to telescope outward, increasing in combined length, but preventsthe tubes from collapsing, or decreasing in combined length, unless thelock is released. This type of locking may be described as a one-waymotion lock. The rod assembly may be described as being length-stablewhen the temporary locking mechanism 650 is engaged. The provisionallocking mechanism 650 allows for adjustment of the length of the rodassembly before the entire system 500 is locked down into a rigidconfiguration. This one-way locking mechanism has an unlockedconfiguration in which the second tubular member can freely translaterelative the first tubular member to increase or decrease the length ofthe external fixation system, and a locked configuration in which thesecond tubular member can freely translate relative to the first tubularmember to increase the combined length of the external fixation systembut is prevented from translating relative to the first tubular memberto decrease the length of the external fixation system. Removal of thetab member 670 converts the one-way locking mechanism from the unlockedto the locked configuration. Tab member 670 may be tethered to thesystem 500, for example via a line, lanyard, split ring, or the like, sothat after tab member 670 is disengaged from the rod clamp assembly 606the tab member 670 is not lost. The tab member 670 may be removed fromthe rod clamp assembly 606 and reinserted into the rod clamp assembly606 repeatedly during a medical procedure.

The locking mechanism 650 includes the binding collar 624, lockingcollar 620, retention pin 628, spring 630 and retainer 632. After tabmember 670 is removed, a closing force is applied by spring 630, theclosing force pushing binding collar 624 against inner tubular element602. In this state, tension may be applied to one or both tubularelements 600 and 602 to translate them coaxially apart, to increasetheir combined length; for example, the second clamp assembly 504 may bedistracted away from the first clamp assembly 502. As the elements arepulled apart binding collar 624 and retention pin 628 are advancedtoward locking collar 620, freeing binding collar 624 from engagementwith inner tubular element 602. Once the desired length of the rodassembly 506 is achieved, and the tension is released, the spring forcecauses binding collar 624 to bind against inner tube 602 provisionallylocking the tubes 600, 602 together and preventing any decrease in theircombined length. The closing force is required to ensure that thelocking action is automatic and occurs without any backlash. In thecontext of this disclosure, automatic locking refers to locking thatdoes not require any additional action by the user to accomplish thelocking; once the pulling force ceases allowing binding collar 624 tohind against inner tube 602, the length of rod assembly 506 is lockedwithout any further steps. It is appreciated that provisional lockingmechanism 650 allows locking of the two tubular elements togetheranywhere along a continuum on the outer surface of inner tubular element602. In other words, the provisional locking mechanism 650 allowslocking of the two tubular elements together at any one of an infinitenumber of locations along the other surface of the inner tubularelement. During system lengthening, binding collar 624 may be parallelwith locking collar 620; during provisional locking, binding collar 624may be angled relative to locking collar 620 as it binds against theinner tubular element.

After provisional locking, further locking of each rod assembly may beaccomplished by turning screw 626. As screw 626 is tightened, the innerdiameter of the locking collar 620 decreases and compresses over the rodslot 616, reducing the effective inside diameter of the large tube 600until it compresses around the outside of the small tube 602. Screw 626and plug 611 may include coarse pitch threads for quick tightening.

Locking screw 604 may also be tightened to more permanently fix thelength of rod assembly 506, and/or to increase the rigidity of the rodassembly 506. The locking screw 604 and inner plug 611 act to remove anybacklash or looseness that may exist between the outer diameter of thefirst end 605 of the small tube 602 and the inner diameter of the largetube 600. The locking screw 604 includes a screw head 634 and a shaft636 with a threaded portion 638. The inner plug 611 includes aprotrusion 642 and a threaded bore 644. As screw 604 is rotated, thethreaded portion 638 of the screw engages the threaded bore 644 of theinner plug 611 and protrusion 642 indexes into one of the slots 640 inthe tube to prevent the plug from spinning as the screw 604 turns.Protrusion 642 may be referred to as a key and slot 640 may be referredto as a keyway. The first end 605 of the inner tube 602 features severalslots 640 that allow the tube to expand as the tapered inner plug 611 isdrawn into it by rotation of the screw 604. Screw 604 may be turneduntil inner tubular member 602 has expanded sufficiently to cause firstend 605 of inner tubular member 602 to fit tightly within outer tubularmember 600, and lock its position relative to outer tubular member 600.The screw head 634 protrudes from the small tube plug 610 and istherefore readily accessible yet largely out of the way.

It is appreciated that other locking assemblies known in the art may beused to clamp the tubular portions together and fix the length of a rodassembly. In an embodiment, a two piece compression lock may be used tofix the length of a rod assembly. The outer tubular element may berotated about the inner tubular element to compress about the innertubular element and lock the length of the rod assembly. In anotherembodiment, a wedge member may be substituted for inner plug 611 toexpand inner tubular element 602 within outer tubular element 604 andlock the tubular elements together. In another embodiment, hydraulicexpansion may be used to lock the tubular elements together at a desiredlength. In another embodiment, a dovetail and tab system may be used tolock the tubular elements together at a desired length. In anotherembodiment, a ball and ramp frictional lock may be used to lock thetubular elements together.

In an embodiment, external fixation system 500 is available in a kit700, as shown in FIG. 11. Kit 700 may include a tray 702, thepre-assembled external fixation system 500, a plurality of bone pins510, 560 and/or 562, a drill guide 704, drill sleeves 706, and/or awrench 708. The kit may be sterile packaged in the peel-pack tray 702,which may be sealed.

In a method of use, kit 700 is opened and the drill guide 704 removed.The drill guide 704 is positioned at a first bone portion on thepatient, drill sleeves 706 are inserted into the drill guide, andpassages are drilled through drill sleeves and guide, through theadjacent tissues, and into the bone portion. The drill sleeves mayprevent soft tissue from wrapping around the drill and/or pin duringthis step. One or more of the bone pins 560, 562 are inserted throughthe drilled passages and fixed in the first bone portion. In analternative embodiment, the pins may be placed without the use of thedrill guide and drill sleeves; in one alternative, the system 500 may beremoved from the kit and positioned so that the first and secondclamping assemblies 502, 504 are on opposite sides of the fracture,joint, or other discontinuity, and the pins may be placed through thefirst clamping assembly 502.

The system 500 is removed from the kit and positioned so that the firstclamping assembly 502 is placed over the one or more bone pins 560, 562with each bone pin 560 and/or 562 received in a pin bore 542. Thefixation bolts 522, 524 are tightened to fix the clamping body 520 tothe bone pin(s). The system 500 may be lengthened or shortened byaxially translating outer tubular members 600 relative to the innertubular members 602. The length of system 500 is adjusted to span thejoint and/or fracture. To adjust the system length, the second clampingassembly 504 may be pulled axially toward or away from the firstclamping assembly 502 to lengthen or shorten the assembly. When thedesired length is achieved, the second clamping assembly 504 may then beused as a drill guide for one or more additional bone pins 560, 562 tobe fixed in the second bone portion. The additional bone pin(s) may beplaced in the second bone portion out of plane from the bone pin(s) inthe first bone portion. After at least one additional bone pin is placedin the second bone portion, the second clamping assembly is mounted onthe additional bone pin(s), and the fixation bolts 522, 524 of thesecond clamping assembly 504 are tightened to fix the second clampingbody 520 to the additional bone pin(s) in the second bone portion. It isnoted that the polyaxial connections allow the system 500 to twistsufficiently to allow the clamping assemblies 502, 504 mount to firstand second sets of bone pins, respectively, which are out of plane fromone another. The tab members 670 are removed. The system 500 islengthened to provide traction, reduce the fracture and establish theproper limb length between the first and second bone portions, the innertubular elements 602 non-rotatably sliding relative to the outer tubeelements 600. The system 500 can be lengthened generally parallel toaxis 541, within the polyaxial range of motion, by grasping and pullingclamping assembly 502 axially away from clamping assembly 504.Alternatively, the practitioner may grasp the patient's limb, at thefoot for example, and pull axially to lengthen the limb and the system500. When lengthening ceases, the system 500 automatically provisionallylocks in a one-way manner as described above, with binding collars 624engaged against inner tubular elements 602, in what may be referred toas primary locking. The provisional locking may occur when the clampingassembly 502 is released from the tension of pulling. In thisarrangement, the practitioner may apply distraction forcesintermittently, and may rely upon the one-way lock to maintain alength-stable construct during periods of no distraction force. This maybe advantageous to the practitioner, as rest periods may be takenwithout sacrificing reduction. The rest periods may also permitreassessment of reduction quality, or they may allow gradual atraumaticstretching of swollen, cramped, or spasming muscles or other softtissues. The system facilitates obtaining an initial reduction followedby an iterative process of refining the reduction without the stress andfatigue associated with constantly maintaining traction on the limb. Forexample, the reduction may be refined by rotating one bone portionrelative to the other bone portion.

After provisional locking at the desired length, at least one of thescrews 626 may be tightened to lock the locking collar 620 around therod assembly, in what may be referred to as secondary locking byactivating a second locking mechanism. The limb or bone portions may befurther manipulated to achieve proper segment alignment; the sphericalportions 612, 614 may polyaxially rotate within their respective innerclamping surfaces 570, 580. For example, one or both of the boneportions may be rotated while the system 500 automatically maintains thedesired length. Once the desired bone alignment is achieved, theclamping bolts 530 on each clamp assembly 502, 504 are tightened to lockthe clamping assemblies 502, 504 to the rod assemblies 506, 508 with theclamping surfaces 570, 580 compressing around the spherical portions612, 614 to prevent further polyaxial motion. Wing nuts 533 may befinger tightened to tighten the clamping bolts 530. The remaining screw626 may also be tightened at this time, if loose. The locking screws 604in each rod assembly 506, 508 are tightened to further lock the relativeposition of the telescoping inner and outer tubular elements 600, 602,in what may be referred to as tertiary locking by activating a thirdlocking mechanism. During the procedure, wrench 708 may be used toadjust the screws and bolts of the assembly 500.

The one-piece assembly 500 and one-way automatic locking of the rodassemblies 506, 508 can be advantageous when quick, secure setting of apatient's limb or joint is desired. In contrast with external fixationsystems which require assembly of separate rods, clamps and otherstructures during the external fixation procedure, system 500 ispre-assembled and packaged as one piece which is easily manipulated in auser's two hands. After mounting to the bone pins, system 500 is easilytelescopically lengthened by pulling one clamping assembly 502 away fromthe other clamping assembly 504; when the clamping assembly is releasedthe automatic one-way locking mechanism prevents collapse or shorteningof the assembly 500. The one-way provisional locking mechanism maintainsthe length of the assembly 500 while final adjustments are made and thesecondary locking mechanisms are deployed.

The system 500 provides single point tightening and loosening a each oneof the locking mechanisms Length can be locked progressively, orunlocked and adjusted, without unlocking the clamps, and vice versa.

For ease of use, indicia or labeling may be provided on locking screwsor other parts. In one non-limiting example, fixation bolts 522, 524 areeach marked with a ‘1’ to indicate that they should be actuated first.Similarly, clamping bolts 530 may be marked with a ‘2’; screws 626 maybe marked with a ‘3’, and locking screws 604 may be marked with a ‘4’ toindicate the proper order of actuation and locking. In otherembodiments, locking may occur in a different order and the screws orparts may be labeled accordingly.

The clamping bodies 520, locking collars 622 and binding collars 624 maybe injection molded in plastic, preferably in a fiber reinforcedmaterial to resist creep under a prolonged load. For examplefiber-filled PEEK (polyetheretherketone) may be used, and mayincorporate glass or carbon fibers. In another embodiment, the clampingbodies are made from machined aluminum. The pins, bolts, screws, nutsand springs may be made of stainless steel or a stainless alloy,preferably non-magnetic. The fixation plates 526-529 and binding collar624 may be made of stainless steel or other metal, preferablynon-magnetic. The locking collar 622, and inner and outer tubularelements 602, 600 may be formed of aluminum. The spherical portions 612,614 may be cast, may be machined from aluminum, or may be molded fromPEEK. Inner plug 611 may be injection molded in plastic, or in otherembodiments may include aluminum or fiber-filled PEEK. Some or all partsmay be radiolucent. It is appreciated that system 500 may be provided invarious sizes and/or lengths so that a practitioner can select a systemsuited to the size or needs of the patient. For example, longer orshorter rod assemblies may be used to build systems with longer orshorter overall lengths. Rods of various diameters may also be availableto scale the external fixation system to the intended use. It is alsoappreciated that in an embodiment, only one rod assembly may be includedin the system. In another embodiment, more than two rod assemblies maybe included in the system, with an appropriate number of clamps forclamping the rod assemblies.

Another embodiment includes an external fixation system 800 which may bereferred to as an ankle spanning system 800 or joint spanning system,although external fixation system 800 may also be used to span afracture, osteotomy, epiphyseal plate, or other discontinuity betweenbone portions. Referring to FIGS. 12-18B, external fixation system 800includes the first clamping assembly 502, the first rod assembly 506 andthe second rod assembly 508, and a clamping subassembly 802.

The clamping subassembly 802, which may be referred to as an ankleclamping subassembly, can connect to and extend between the first andsecond rod assemblies 506, 508, and includes a first clamping strutassembly 804, a second clamping strut assembly 806, a spanning member808, and a pin clamp assembly 810. Two calcaneal pins 812, 814 extendbetween the first and second clamping strut assemblies 804, 806; eachcalcaneal pin includes a threaded portion 815. The first clampingassembly 502, first rod assembly 506 and second rod assembly 508 are asdescribed above with reference to FIGS. 1-10; in this embodiment the rodassemblies may be shorter than those depicted in FIGS. 1-10. Theexternal fixation system 800 can provide rigid fixation of the anklejoint, to stabilize the foot and ankle with respect to the tibia, forexample in the case of a lower tibial fracture or an injured anklejoint.

Referring to FIGS. 14-16, the first and second clamping strut assemblies804, 806 may be mirror images, or may be identical to one another exceptfor the direction in which locking bolts, screws, or pins are inserted;thus the description of first clamping strut assembly 804 also appliesto assembly 806. First clamping strut assembly 804 includes a clampingstrut 820, first and second fixation plates 822, 824, spacing member826, first fixation bolt 828, second fixation bolt 830, nut 832, afixation member 834 and two dowel pins 836. The clamping strut 820includes a strut portion 840, a split clamp portion 842, and a pin dampportion 844. From a side view, the clamping strut may be generallyY-shaped. The strut portion 840 may be straight, and oval in crosssection, although other cross-section shapes such as circular, square orrectangular are contemplated within the scope of the disclosure. Thestrut portion 840 includes a fixation member bore 841 and may includeadditional bores to receive dowel pins, to enable connection to thespanning member 808. At least one of the bores in the strut portion maybe threaded. In an embodiment, fixation plates 822, 824 are structurallythe same as fixation plates 526-529. Each fixation plate 822, 824includes a bolt opening 870 and several pin openings 872. Bolt and pinopenings 870, 872 may be threaded or non-threaded. It is noted that thethreaded portion 815 on each calcaneal pin may be smaller diameter thanthreading in the pin openings 872 on the fixation plates, allowing thecalcaneal pins to be freely inserted through the fixation plates.

The split clamp portion 842 of the clamping strut 820 includes first andsecond damp arms 850, 852 which face one another and encircle aspherical clamping surface 854, which is interrupted by a gap 856. Afixation bore 858 extends through a distal end of the split clampportion 842, and is interrupted by the gap 856. When operativelyassembled as in FIG. 14, the spherical portion 612 of rod assembly 506is received within the clamp arms 850, 852 and encircled by thespherical clamping surface 854 so that the spherical portion 612 iscaptive within the clamp arms 850, 852. The rod assembly 506 may bepolyaxially adjustable within the split clamp portion 842 until adesired position is reached. Second fixation bolt 830 may be actuated todraw the first and second clamp arms 850, 852 together, closing the gap856 and locking the position of the rod assembly 506 relative to theclamping strut 820.

The pin clamp portion 844 includes a first support arm 860 having afirst recess 862, opposite a second support arm 864 having a secondrecess 866, each recess shaped to receive a fixation plate 822, 824. Thesupport arms 860, 864 are separated by an arm gap 868. When operativelyassembled as in FIG. 14, the first fixation plate 822 is received infirst recess 862, second fixation plate 824 is received in second recess866, and spacing member 826 is received between the support arms 860,864 in the arm gap 868. First fixation bolt 828 extends through boltopening 870 the first fixation plate 822, through the spacer member 826and into the bolt opening 870 in second fixation plate 824. Calcanealpins 812, 814 extend transversely through pin openings 872 in thefixation plates, through the support arms 860, 864, and through the armgap 868. When fixation bolt 828 is tightened, threads on the fixationbolt 828 may engage threads in the bolt opening 870 on the secondfixation plate 824 so that tightening the bolt draws the first andsecond fixation plates toward one another and one or both of fixationplates 822, 824 may be deformed. The pin openings 872 frictionally bindagainst calcaneal pins 812, 814 preventing them from further axialtranslation relative to the clamping strut assembly 804. It isappreciated that in other embodiments, other methods of pin capture orfixation known in the art may be used.

Referring to FIGS. 17A-17C, spanning member 808 includes first andsecond attachment sections 880, 882 which are bridged by a span section884. In the embodiment shown span section 884 is curved to fit over apatient's appendage. The size, shape and curvature of the spanningmember 808 may be varied to accommodate variations in patient size orappendage configuration; in some embodiments the spanning member may bestraight. Each attachment section includes a first bore 886 and one ormore secondary bores 890. On an outer side of the member 880, a recess888 surrounds the first bore 886. As seen in FIGS. 14 and 16, spanningmember 808 may be operatively attached to each clamping strut assembly804, 806. Dowel pins 836 are received in openings on the clamping struts820 and in the secondary bores 890 in the spanning member. Fixationmember 834 extends through first bore 886 and into bore 841 on theclamping strut 820 to secure the spanning member 808 to the clampingstrut 820. A head portion of the fixation member 834 is received in therecess 888 to provide a low profile to the assembly.

It is appreciated that variations in the configuration of the clampingstrut assemblies 804, 806 and the spanning member 808 may occur. Forexample, in another embodiment the strut portions may be shorter thanthose depicted, and the attachment sections 880, 882 may extend towardthe strut portions. In another embodiment, a separate spanning membermay not be present; instead the spanning member may be integrally formedwith the clamping strut assemblies to bridge between them. In anotherembodiment, the spanning member may be absent; the calcaneal pins mayform the connection between the clamping strut assemblies.

Referring to FIGS. 18A and 18B, pin clamp assembly 810 includes a clampbody 900 having a pin clamp portion 902 and a spanning member clampportion 904. The clamp portions 902, 904 may be angled relative to oneanother. The pin clamp portion 902 includes first and second sphericalopenings 906, 908. A slot 910 intersects both spherical openings. Afirst split sphere 912 is received in the first spherical opening 906and a second split sphere 914 is received in the second sphericalopening 908. A first fixation pin 916 is received through the firstsplit sphere 912 and a second fixation pin 918 is received in the secondsplit sphere 914. The split spheres are polyaxially adjustable withinthe spherical openings, allowing the trajectories of fixation pins to beadjusted to connect with targeted bone portions, such as a metatarsalbone, or other structures. A first bolt opening 920 extends through thepin clamp portion 902 transverse to the spherical openings, and receivesa first clamping bolt 922. When clamping bolt 922 is tightened, thewidth of slot 910 decreases and the spherical openings 906, 908 arecompressed around the spherical members 912, 914, locking the positionsof the spherical members and the captured pins 916, 918.

Spanning member clamp portion 904 includes a member opening 928surrounded by a member clamping surface 930. Both the member opening 928and clamping surface 930 are interrupted by a member clamping gap 932. Asecond bolt opening 934 extends through clamp portion 904 and a secondclamping bolt 936 extends through the bolt opening 934, bridging the gap932. When operatively assembled as in FIG. 12, for example, spanningmember 808 is received in the member opening 928, and the pin clampassembly 810 may be translated along the spanning member 808 until adesired or targeted position is reached. Second clamping bolt 936 isactuated to close the gap 932 and compress clamping surface 930 aroundthe spanning member 808, preventing any further translation of the pinclamp assembly 810 relative to the spanning member 808.

In an embodiment, external fixation system 800 is available in a kit.The kit may include a tray, the pre-assembled external fixation system800, a plurality of bone pins 560, 562, 916, 918, calcaneal pins 812,814, a drill guide 704, drill sleeves 706, and/or a wrench 708. The kitmay be sterile packaged in the tray.

In a method of use of system 800 to immobilize an ankle joint, one ormore of the following steps may be present. The tray is opened and thesystem 800 is removed from the tray. With reference to FIG. 12, thefirst bone pin 560 is placed in the tibia. The pre-assembled system 800with clamping assembly 502 is placed over the first bone pin 560, withpin 560 extending through a pin opening 542 in clamp body 520. Thespanning member 808 is rested over the foot, with the first and secondclamping strut assemblies 804, 806 along either side of the foot in agenerally aligned position. Using the clamping assembly 502 as a guide,the second tibial pin is extended through another pin opening 542 inclamp body 520 and into the tibia. The clamping assembly 502 is lockedto the bone pins 560, 562 by tightening fixation bolts 522, 524, Thefirst and second clamping strut assemblies 804, 806 are aligned to thecalcaneus and one of the first or second calcaneal pins 812, 814 isdriven through first and second clamping strut assemblies 804, 806 aswell as the bone. The polyaxial alignment of the rod assemblies 506, 508is adjusted relative to the clamping assemblies 502, 804 and 806. Thepolyaxial clamps are provisionally locked by tightening clamping bolt530 in clamping assembly 502, and by tightening fixation bolts 830 inclamping strut assemblies 804, 806. The pin clamp assembly 89 is slidalong the spanning member 808 until it provides the proper approachangle to the great toe metatarsal. The position of the pin clampassembly 810 on the spanning member is locked by tightening clampingbolt 936 in the spanning member clamp portion 904. One or bothmetatarsal pins 916, 918 are placed through the polyaxial split spheres912, 914 and into the metatarsal. The pins 916, 918 are locked into thepin clamp portion 902 by tightening clamping bolt 922.

The other of the first and second calcaneal pins 812, 814 is insertedthrough the first and second clamping strut assemblies 804, 806 as wellas the bone. The calcaneal pins 812, 814 are locked into the first andsecond clamping strut assemblies 804, 806 by tightening fixation bolts828 to frictionally lock the pins to the clamping struts 820. The tabmembers 670 are removed from the rod assemblies 506, 508. If required,the limb is placed in traction to re-establish the proper limb length.When the traction is released, the one-way provisional locking of therod assemblies as described previously will maintain the establishedlength. Binding collar 624 engages against inner tube 602 to preventtelescopic collapsing, or a decrease in the length of the rod assembly.The limb position may be adjusted as necessary, which may includeloosening polyaxial clamping bolts 530, 830, adjusting the relativeposition of the rod assemblies and re-tightening the polyaxial clampingbolts 530, 830. Screws 626 on locking collars 620 are tightened toprevent axial translation of the inner and outer tubes 602, 600 relativeto one another. Locking screws 604 are tightened to expand each innertube member 602 and lock its position relative to outer tube member 600.

Referring to FIGS. 19 and 20, an external fixation system 1000 is atwo-level system which includes system 500, which may span a knee joint,and system 800, which may span an ankle joint. Both systems 500, 800 aremounted on a common set of bone pins 560, 562 which may be mounted in atibia. System 1000 may provide rigid fixation of the both the knee andankle joints. Systems 500 and 800 may be vertically stacked on one setof pins without further modification as shown in FIGS. 19 and 20. Inanother embodiment, the clamp bodies 520 may be modified to allowsystems 500 and 800 to be mounted horizontally relative to one another,for example adjacent to one another along second axis 535.

In a method of use of external fixation system 1000, bone pin 560 ismounted in a tibia. External fixation system 800 is mounted on bone pin560 and as described previously, through the step of the one-wayprovisionally locking of the rod assemblies. After external fixationsystem 800 is mounted and provisionally locked, external fixation system500 is mounted on to bone pins 560, 562 and the rod assemblies areprovisionally locked as described previously for system 500. After theprovisional locking of systems 500 and 800, final limb adjustments andlocking steps for both systems can be iteratively carried out as needed.It will be appreciated that additional systems 500 and/or 800 may bemounted sequentially to extend the zone of fixation as far as necessary.

Another embodiment includes an external fixation system 1100 which maybe referred to as a wrist spanning system 1100 or joint spanning system,although external fixation system 1100 may also be used to span afracture, osteotomy, epiphyseal plate, or other discontinuity betweenbone portions. Referring to FIGS. 21-27, external fixation system 1100includes a first clamping assembly 1102, a second clamping assembly1104, and the first rod assembly 506. The rod assembly 506 extendsbetween and connects the clamping assemblies 1102, 1104 into the singlesystem 1100. The rod assembly 506 may be scaled in length and/ordiameter to an appropriate size for the wrist. The clamping assembliesmay be referred to as support elements or members, as they support therod assembly. The first and second clamping assemblies may be mirrorimages, or may be identical to one another. As described above, usingidentical assemblies in a system may enable the entire system to beproduced more cheaply and/or quickly than a system in which eachseparate component or assembly is unique.

In use, system 1100 can be secured to the patient in one piece, as aunit. First clamping assembly 1102 may be fixed to a first bone portionby one or more fixation pins 510. Bone screws, bone pins, wires, and/orother fasteners may be used in place of or in combination with fixationpins 510. Second clamping assembly 1104 may be fixed to a second boneportion by additional fixation pin(s) 510. The rod assembly 506,extending between the clamping assemblies, may span a joint or fracturebetween the first and second bone portions. After the clampingassemblies 1102, 1104 are fixed to the bone portions, the rod assembly506 may be lengthened or shortened to a desired length and provisionallylocked to stabilize the joint or fracture. Following the provisionallocking, the polyaxial connections of the assembly may be adjusted, thenmore permanently locked.

Referring to FIGS. 22-26, clamping assembly 1102 is shown in moredetail. Clamping assembly 1104 may be a mirror image, or may beidentical to damping assembly 1102 and will not be described in furtherdetail; the description of clamping assembly 1102 also applies toclamping assembly 1104. Clamping assembly 1102 includes a clamp body1120 which is formed as a single piece. Clamping assembly 1102 furtherincludes first fixation bolt 1122; first and second fixation plates1126, 1127; a clamping bolt 1130; first nut 1132; and second nut 1133.The fixation plates may be referred to as locking plates. The rodassembly 506 is polyaxially adjustably connected to the clampingassembly 1102 via a clamp 1134 which is formed as part of the clampingbody 1120. Two bone pins 560, 562 extend through the clamping body 1120to fix the clamping assembly 1102 to a bone portion. In anotherembodiment, only one bone pin may be used in each clamping assembly.

Referring to FIGS. 21-26, clamp body 1120 may be T-shaped and includesan upper or first surface 1112 and a lower or second surface 1114opposite the first surface. The clamp body 1120 further includes a firstarm 1138 and a second arm 1140 which extend along a first axis 1141,perpendicular to the first clamp 1134, which extends along a second axis1135. First axis 1141 may be parallel to the longitudinal lengths of rodassembly 506 when the system 1100 is in a neutral or orthogonalarrangement. A bolt opening 1144 extends through the clamping body 1120in the same direction as the pin openings 1142, 1152 described below. Inthe example shown, the bolt and pin openings extend in a directionperpendicular to the first axis 1141 and the second axis 1135. A firstslot 1148 is recessed into the first surface 1112, and a second slot1150 is recessed into the second surface 1114, opposite the first slot.The first and second slots are elongated, occupying the majority of thelength of the first and second arms 1138, 1140, and the slots areparallel with first axis 1141. A plurality of pin openings or bores 1142extend through the arms between the first and second slots 1148, 1150,each pin bore sized to receive a bone pin 510. First fixation plate 1126is housed in the first slot 1148 and second fixation plate 1127 ishoused in the second slot 1150. Each fixation plate 1126, 1127 includesat least one plate pin opening 1152, and one of a threaded plate boltopening 1154 or a non-threaded plate bolt opening 1155. Each fixationplate 1126, 1127 is elongated, having a first extension 1156 and asecond extension 1158.

The bone pins 560, 562 are received in pin openings 1142 of clamp body1120. Each bone pin may pass through a plate pin opening 1152 in afixation plate, through the first slot 1148, through a pin bore 1142,through the second slot 1150, and out through a plate pin opening 1152in another fixation plate. The opening for the pins may be non-threadedand/or smooth, to allow the pins 560, 562 to initially be axiallytranslatable relative to the arms 1138, 1140. The translation allows foradjustability of the height of the system 1100 relative to a patient'slimb, which may be advantageous if there is tissue swelling, an openwound, and/or a skin abrasion on the limb. It is appreciated that thebone pins may be placed in one or any combination of the pin openings1142.

Referring to FIG. 25, the first fixation bolt 1122 passes through anon-threaded bolt opening 1155 in first fixation plate 1126, into thefirst slot 1148, through a bolt opening 1144 and out through second slot1150 and a threaded plate bolt opening 1154 in second fixation plate1127. As the threads of bolt 1122 engage threaded plate bolt opening1154, the center portion of second fixation plate 1127 is drawn towardthe center portion of first fixation plate 1126 against the resistanceof first and second extensions 1156, 1157 bearing in slots 1148, 1150,causing one or both of fixation plates 1127, 1126 to be elastically orplastically deformed. As a result of the elastic or plastic deformation,the plate pin openings 1152 frictionally bind against pin 562,preventing pin 562 from further axial translation relative to the clampbody 1120. As the plates 1126, 1128 deform, they may bow and decrease inlength, which pushes the pin 562 against the side wall of the pin bore1142. This force creates a secondary locking action relative to the pin562. It is appreciated that in other embodiments, other methods of pincapture or fixation known in the art may be used.

Turning to FIGS. 23-24 and 26, the clamp 1134 is shaped to retain orclamp rod assembly 506 while allowing telescoping movement of the rodassembly to lengthen or shorten the rod assembly. Clamp 1134 has aninner clamping surface 1170 which is spherical in the illustratedembodiment; in other embodiments the clamping surfaces may be partiallyspherical, conical, cylindrical, flat, polygonal, or another shape. Theinner clamping surface 1170 is interrupted by a clamp gap 1172 boundedby opposing first and second clamp surfaces 1174, 1176. In the exampleshown the inner clamping surface 1170 is smooth, but in an alternativeembodiment it may be ridged or roughened. A bore 1190 extends throughthe clamp 1134, parallel to second axis 1135, intersecting clamp gap1172. The bore 1190 includes a first recess 1192 at one end and a secondrecess 1194 at the opposite end. One or more chambers 11196 extend intothe clamp body 1120 between the pin openings 1142, and may provide forweight reduction for the clamp body. Clamping bolt 1130 extends throughbore 1190 and engages nut 1132. As the clamping bolt 1130 engages thenut 1132, the nut 1132 is captured in second recess 1194. Furtheractuation of bolt 1130 draws nut 1132 toward the bolt head, engagingrecess 1194 and closing gap 1172. Nut 1133, which may be a wing nut, mayalso be actuated to tighten bolt 1130. As seen in FIG. 21, when rodassembly 506 is assembled with clamp assemblies 1102, 1104 as shown andbolt 1130 is tightened as described, the rod assembly is gripped in theclamps 1134 and prevented from any movement, for example axial,rotation, or polyaxial, relative to the clamp body 1120.

In an embodiment, external fixation system 11100 is available in a kit,similar to that shown in FIG. 11. The kit for external fixation system1100 may include a tray, the pre-assembled external fixation system1100, a plurality of bone pins 560 and 562, a chill guide 704, drillsleeves 706, and/or a wrench 708. The kit may be sterile packaged in apeel-pack tray, which may be sealed.

A method of use of external fixation system 1100 may be similar to, oridentical to, that described above for external fixation system 500.

The systems disclosed herein may provide advantages over externalfixation systems known in the art. For example, providing pre-assembledsystems such as 500, 800, or 1100 which are anatomy-specific can reducethe number of parts or inventory necessary to perform an externalfixation procedure, compared to systems which are provided as acomprehensive kit of loose parts. Also, having a pre-assembled systemcan minimize unanticipated disassembly during an external fixationprocedure and during tightening and adjustment of the system. Thepre-assembled system may therefore provide a low-stress user experiencefor the practitioner, for example, by eliminating tedious intraoperativeassembly or unanticipated disassembly. Use of the pre-assembled systemsdisclosed herein also reduces or eliminates operating room or proceduretime which, for other systems known in the art, is spent assembling afixation system on the back table. The one-way locking mechanism mayretain limb length during tightening and adjustment of the systemwithout requiring constant distraction by the surgeon. The one-waylocking mechanism contributes to ease of obtaining fracture reduction,and the provisional locking is secure enough to allow easy adjustment ofthe reduction while the system is provisionally locked. The removabletab member 670 provides quick conversion between the unlockedconfiguration and the locked configuration, allowing quick and efficientdistraction and reduction. The systems disclosed herein can be appliedto a patient by one or two practitioners, which may reduce the number ofpractitioners needed and overall procedure cost.

In addition to the embodiments shown herein to span the knee, ankle,and/or wrist joints, it is appreciated that principles taught herein maybe applied to external fixators and fixation methods for other joints,including but not limited to the elbow, wrist, carpal, tarsal,phalanges, hip, sacrum, shoulder, cranium, and/or intervertebral joints.The technology disclosed herein may also be applied to external fixationand fixation methods for fractures rather than joints.

The apparatus disclosed herein may be made from low cost materials, suchas aluminum and/or plastic, using low cost manufacturing techniques suchas lathe and mill. In some embodiments, the system may be so inexpensiveas to be single-use disposable. In this situation, there would be nore-processing or re-stocking fees charged to the owner of the apparatus.

It should be understood that the present system, kits, apparatuses, andmethods are not intended to be limited to the particular formsdisclosed. Rather, they are to cover all modifications, equivalents, andalternatives falling within the scope of the claims.

The claims are not to be interpreted as including means-plus- orstep-plus-function limitations, unless such a limitation is explicitlyrecited in a given claim using the phrase(s) “means for” or “step for,”respectively.

The term “coupled” is defined as connected, although not necessarilydirectly, and not necessarily mechanically.

The use of the word “a” or “an” when used in conjunction with the term“comprising” in the claims and/or the specification may mean “one,” butit is also consistent with the meaning of “one or more” or “at leastone.” The term “about” means, in general, the stated value plus or minus5%. The use of the term “or” in the claims is used to mean “and/or”unless explicitly indicated to refer to alternatives only or thealternative are mutually exclusive, although the disclosure supports adefinition that refers to only alternatives and “and/or.”

The terms “comprise” (and any form of comprise, such as “comprises” and“comprising”), “have” (and any form of have, such as “has” and“having”), “include” (and any form of include, such as “includes” and“including”) and “contain” (and any form of contain, such as “contains”and “containing”) are open-ended linking verbs. As a result, a method ordevice that “comprises,” “has,” “includes” or “contains” one or moresteps or elements, possesses those one or more steps or elements, but isnot limited to possessing only those one or more elements. Likewise, astep of a method or an element of a device that “comprises,” “has,”“includes” or “contains” one or more features, possesses those one ormore features, but is not limited to possessing only those one or morefeatures. Furthermore, a device or structure that is configured in acertain way is configured in at least that way, but may also beconfigured in ways that are not listed.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. It isappreciated that various features of the above-described examples can bemixed and matched to form a variety of other alternatives. For example,a clamping body or assembly described for one system may be used withanother system. Features of instrumentation from one example may beapplied to instrumentation from another example. As such, the describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. A method for external fixation of a limb, the limb having a firstbone portion and a second bone portion, the method comprising: securinga first bone pin to the first bone portion; securing a second bone pinto the second bone portion; attaching a pre-assembled external fixationsystem to the first bone pin, the external fixation system comprising:first and second clamp assemblies, first rod assemblies, and a one-waylocking mechanism; the first rod assembly joined to each of the firstand second clamp assemblies, the first and second clamp assemblies aopposite longitudinal ends of the first rod assemblies; the first clampassembly received over the first bone pin; attaching the externalfixation system to the second bone pin, the second damp assemblyreceived over the second bone pin; applying tension to distract thefirst clamp assembly longitudinally away from the second clamp assemblyto increase a length of the external fixation system between the firstclamp assembly and the second clamp assembly; and releasing the tensionon the first clamp assembly, wherein when the tension on the first clampassembly is released the one-way locking mechanism automatically engagesto prevent the length of the external fixation system from decreasing.2. The method of claim 1, comprising: opening a package; and removingthe pre-assembled external fixation system as a single unit from thepackage.
 3. The method of claim 1, wherein each rod assembly comprises aremovable tab, the method comprising: removing the tab to activate theone-way locking mechanism, wherein prior to removal of the tab, theexternal fixation system is freely adjustable to increase or decreasethe length of the external fixation system between the first clampassembly and the second clamp assembly.
 4. The method of claim 1,comprising a second rod assembly, the second rod assembly joined to eachof the first and second clamp assemblies.
 5. The method of claim 4,wherein the first clamp assembly is identical to the second clampassembly, and wherein the first rod assembly is identical to the secondrod assembly.
 6. The method of claim 1, wherein the one-way lockingmechanism automatically engages the rod assembly to prevent the lengthof the external fixation system from decreasing.
 7. The method of claim6, wherein the one-way locking mechanism automatically engages the rodassembly at a non-discrete location to prevent the length of theexternal fixation system from decreasing.
 8. The method of claim 1,wherein the rod assembly comprises an inner tubular member received inan outer tubular member, wherein the one-way locking mechanism is afirst locking mechanism, wherein the one-way locking mechanism ismounted to the outer tubular member, wherein activating the one-waylocking mechanism comprises: directly engaging the one-way lockingmechanism with the inner tubular member prevent the inner tubular memberfrom translating relative to the outer tubular member in a firstdirection.
 9. The method of claim 8, wherein the one-way lockingmechanism comprises a collar encircling the inner tubular member,wherein the collar frictionally engages with the inner tubular member toprevent the inner tubular member from translating relative to the outertubular member in the first direction.
 10. The method of claim 8,comprising: activating a second locking mechanism to further prevent theinner tubular member from translating relative to the outer tubularmember in the first direction and also in a second direction oppositethe first direction.
 11. The method of claim 10, wherein the rodassembly comprises the second locking mechanism, the second lockingmechanism comprising a clamp encircling the outer tubular member, themethod comprising: compressing the clamp around the outer tubularmember; and compressing the outer tubular member around the innertubular member.
 12. The method of claim 10, comprising: activating athird locking mechanism to further prevent the inner tubular member fromtranslating relative to the outer tubular member.
 13. The method ofclaim 12, wherein the rod assembly comprises the third lockingmechanisms, the third locking mechanism comprising a plug received inthe inner tubular member, the method comprising drawing the plug withinthe inner tubular member to expand a portion of the inner tubularmember.
 14. The method of claim 1, comprising: polyaxially adjusting theposition of the first rod assembly relative to the first clamp assembly;and compressing the first clamp assembly about the first rod assembly tolock the position of the first rod assembly relative to the firstclamping assembly.
 15. The method of claim 1, comprising: locking thefirst clamping assembly to the first bone pin.
 16. The method of claim15, wherein the first clamping assembly houses a first fixation plateand a second fixation plate, wherein locking the first clamping assemblyto the first bone pin passing the first bone pin through the first andsecond fixation plates; and deforming the first and second fixationplates to bind against the first bone pin.
 17. The method of claim 1,comprising: passing a third bone pin into the first clamping assembly;and securing the third bone pin to the limb.